A pipe clip of plastic material, for example as disclosed in German patent specification No. 2 306 969, comprises a mounting portion carrying two clamps for the conduits, and a stirrup portion which fits over the clamps and which has a bar portion engaging therebetween. The free ends of the limb portions of the clamps are increased in thickness outwardly in a bead-like configuration, and the generally U-shaped stirrup portion has catches on the insides of its two limbs, which engage behind the beads on the two outermost limb portions of the clamps; the stirrup portion also has catches which are disposed in opposite relationship on its bar portion and which engage behind the outer beads on the two clamp limb portions which are towards the bar portion, to provide a snap-type closure. While that arrangement provides that the stirrup portion is adequately fixed to the mounting portion, nonetheless a snap-type closure arrangement of that kind also has the result that the clamping effect for clamping the conduits or pipes which are to be fixed in the clamps is smaller when the stirrup portion is fitted into position, than while the stirrup portion is being fitted. Particularly under disadvantageous operating conditions, for example when dealing with sets of injection conduits or pipes, which are to be held together by the pipe clips, between an injection pump and the associated injection nozzles of a diesel engine or other fuel-injection engine, vibration and elevated temperatures may occur, which make it impossible to use a soft-elastic plastic material. If however a correspondingly hard plastic material is employed in order to avoid the above-mentioned disadvantage, then the permanent clamping action which can be produced by the above snap-type closure arrangements is no longer adequate reliably to hold the conduits in position in the desired manner, having regard to tolerances in respect of diameters, both on the conduits to be clamped and also on the clamps of the pipe clip. The pipe clips can slip out of the positions in which they are intended to be disposed, and may lose their desired clamping effect.
When pipe clips are used on injection conduits of internal combustion engines, it is also important for the injection conduits to be reliably clamped at the pipe clip, in such a way as to prevent them from slipping or turning, for the reason that the pipe clips are also employed, before the injection conduits are mounted to the internal combustion engine, to connect the injection conduits together in sets, with the injection conduits already being prebent into the configuration corresponding to the way in which they will be subsequently fitted to the internal combustion engine. In that way, an entire set of injection conduits is taken to the point of mounting thereof, in the form of an assembled unit, so that, at the point of mounting, the injection conduits can be connected to an associated injection pump and to the associated injection nozzles on the engine, by way of the connecting nipples at the ends of the conduits and suitable cap nuts, without the need for further work in matching the conduits to their condition of installation. That simplified method of connecting the conduits in position should also be retained if, after a prolonged period of operation of the internal combustion engine, the injection conduits have to be temporarily removed for any reason.
Because of the above-indicated difficulties, metal pipe clips are also used nowadays on fuel-injection internal combustion engines. The conduits which are to be fixed in position are surrounded at each pipe clip by a rubber member which is more or less softly elastic and which compensates for tolerances. The conduits are clamped in position by way of clamping screws which fix the stirrup portion to the mounting portion, which is thus a comparatively expensive way of fixing the conduits.